I think Alucard missed his friends. They were his only friends, and they just up amd left him. We know that he's mentally like 13 so I imagine when the gooks seduced him he didn't freak out because he assumed this was the ultimate expression of friendship, an exercise of trust and intimacy. That's why he cried, he must have been thinking "so this is what I've been missing out on."
I'm conflicted. Manipulating an innocent being like this only to betray him would be a monstrous thing, but seeing as it came out of nowhere it rings hollow. It would have been better if it spent another season with them continuing to milk Alucard for information, with him slowly catching on that they don't care about him.
There were 3 betrayals this season, but only Lenore's felt like it made sense. The Judge's came out of nowhere, the Gooks came out of nowhere, at least hers was heavily telegraphed. >>Ya know Lenore, I've been thinking. I used to think vampires were amoral hedonistic sociopath leeches, but you're being nice to me because you want something, so you can't be all bad>>That's nice Hector. Wanna have sex?>>D'ok!